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(11) | EP 0 169 722 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Drip feed device |
| (57) A drip feed device connectable to a source of medical fluid, such as a fluid filled
hypodermic syringe, comprises a drip chamber and an adapter having a first passageway
which allows fluid communication between the syringe and the drip chamber and a second
passageway which provides an air vent from outside the drip chamber to the syringe.
The second passageway may comprise a cannula which extends into the fluid upon attachment
of the drip chamber with the syringe. A ball valve may be disposed in the second passageway
to allow air to flow into the syringe to replace the dispensed fluid but to prevent
fluid flow from the syringe through the second passageway. |
[0001] This invention relates generally to drip feed devices used for administration of IV solutions to patients. More particularly, this invention relates to an attaching means between a drip chamber and an air-tight fluid source to permit venting of the fluid source during flow of fluid from the source to the drip chamber. This invention is particularly, though not exclusively, useful for the administration of IV solutions to a patient through a drip chamber from a fluid source such as a hypodermic syringe.
[0002] In numerous health care situations, there is a need to intravenously administer precise quantities of a particular fluid medicament to a patient over an extended period of time. Furthermore, the precise quantities of fluid medicament are often needed in only small quantities for a one-time infusion. On such occasions, the use of large or bulky IV bottles or bags are ineffective, awkward and inconvenient.
[0003] A solution to this problem is to use standard hypodermic syringes as the fluid source container. Generally, such syringes are readily available and provide an effective means for the precise measurement of small fluid quantities. Syringes, however, are typically operated by hand and this can be inconvenient when infusion over an extended period of time is required. Under such circumstances, use of an IV administration set may be more appropriate. Thus, there is a need to somehow incorporate the use of a hypodermic syringe with the use of an IV administration set.
[0004] Whenever an administration set is used, it is particularly important there be some visual indication of fluid flow in the set. Typically, a drip chamber is used for this purpose. Thus, if a syringe is used to collect a precisely measured amount of fluid medicament to be administered to a patient, there is a need for a drip chamber that can be attached directly to the syringe.
[0005] The use of a syringe in an administration set may be particularly appropriate when a "piggyback" system is desired. More particularly, as will be appreciated by those skilled in the art, the drip chamber of the present invention is well suited for incorporation into a piggyback system such as the one disclosed in pending Appli- cation Serial No. 561,958.
[0006] When a syringe is required for the above purposes, the engagement means between syringe and drip chamber must overcome certain inherent problems. Firstly, fluid filled syringes are typically air-tight. Thus, they must be vented if fluid is to flow therefrom in a regular and predictable manner. Secondly, the dispensing nozzle of a syringe is typically of such a reduced cross-sectional area that fluid and venting air cannot flow therethrough simultaneously. Therefore, there is a need to provide separate passageways for fluid flow and for venting air flow. Preferably, as in the present invention, the necessarily simultaneous flow of fluid and venting air can be accomplished through the dispensing nozzle of the syringe without alteration or modification of the syringe.
[0007] Well known in the art are vented drip chambers with attaching means of the type disclosed in U.S. Patent No. 3,316,908 to Burke in which a spike is used to connect the drip chamber to the fluid source. Such devices, however, do not permit attachment of the drip chamber to a hypodermic syringe or other fluid container having a threadable luer lock attachment means. Also well known in the art are devices such as disclosed in U.S. Patent No. 3,822,700 to Pennington wherein a vented means for attaching drip chambers to a fluid source has an additional passageway for the addition or withdrawl of fluids from the fluid source. In these devices, however, a spike is used to effect engagement of the drip chamber with the fluid source. There is, therefore, still the need for a vented drip chamber which is engageable with a standard hypodermic syringe or with any fluid container which must be accessed by some means other than through a spike penetrable stopper.
[0008] It is an object of the prevent invention to provide a vented drip chamber which is engageable with an air-tight fluid container having a standard threadable luer type engagement access means. Another object of this invention is to provide an easy-to-use, relatively inexpensive disposable drip chamber which can be easily attached to a hypodermic syringe to visually monitor the flow of a precisely measured amount of fluid medicament through an IV administration system to a patient.
[0009] According to the present invention we provide a drip feed device for observing the flow of a medical fluid from a fluid source comprising:
a drip chamber;
an adapter having a first end provided with means for engaging a fluid source and a second end having the drip chamber mounted thereon, said adapter including:
a fluid passageway extending from said first end to said second end to provide fluid communication between said fluid source and said drip chamber; and
an air passageway extending from said first end to a position outside said container to vent air to said fluid source.
[0010] The invention is more particularly described with reference to the accompanying drawings in which similar reference characters refer to similar parts, and in which:
Figure 1 is a front elevational view of the drip feed device in connection with a hypodermic syringe;
Figure 2 is a cross-sectional view of a portion of the drip feed device and syringe with portions broken away for clarification;
Figure 3 is a cross-sectional view of the attachment between the drip feed device and the syringe as seen along the line 3-3 in Figure 2; and
Figure 4 is a cross-sectional view of the drip feed device as seen in Figure 2 with the hypodermic syringe removed.
[0011] The drip feed device comprises an adapter 34 and a drip chamber, generally designated 10, shown in operative connection with a syringe 12 in Figure 1. As seen in Figure 1, the drip chamber 10 is used as part of an IV administration set between a fluid soruce, such as the syringe 12, and an IV tube 14. When so used, drip chamber 10 permits visual inspection of fluid flow in the system as IV fluid passes through the IV tube 14 and into a pump or controller (not shown) for subsequent infusion into a patient.
[0012] Figures 2 and 4 provide a detailed cross-sectional view of a portion of the drip chamber 10 of the particular structure for the drip chamber 10. Specifically, as seen in Figures 2 and 4, the drip chamber 10 includes a transparent chamber 16 which is attached to a housing 32 by any means well known in the art. Formed onto the housing 32 and extending into transparent container 16 of drip chamber 10 is a drop former 18. As will be appreciated by those skilled in the art, drop former 18 may be formed with a bevel 30 to assist in the formation of drops as fluid passes through drop former 18 and into transparent container 16. The sidewalls of container 16 are preferably made of a semi-rigid transparent material which will permit drip chamber 10 to be squeezed and thereby cause a partial filling of container 16 prior to operation of the administration set.
[0013] An adapter 34, shown in both Figure 2 and Figure 4, is formed with a fluid passageway 22. Adapter 34 is connected to housing 32 by any means well known in the art and is attached thereto in a manner to extend fluid passageway 22 through housing 32 to establish fluid communication between a fluid source such as the syringe 12 and drop former 18 in container 16.
[0014] Also formed into housing 32 and the adapter 34 is an air passageway 24. More specifically, as seen in Figure 2 and Figure 4, air passageway 24 is defined by a cannula 20 which is attached in fluid-tight relationship with the adapter 34 by any means well known in the art. With this attachment an air passageway 24 is defined from the hollow cannula 20 into the housing 32. Termination of the air passageway 24 is provided by an air filter 28 which can be of any type well known in the art and which is provided in the present invention to prevent contaminants from the atmosphere from entering into the fluid system. In the preferred embodiment, cannula 20 is made of a rigid material such as stainless steel.
[0015] As seen in Figures 2 and 4, ball valve 44 is disposed within the air passageway 24 of air filter housing 26. Ball valve 44 is positioned to provide an air seal at the point of contact between ball valve 44 and shoulder 46 in the air passageway 24 when fluid attempts to enter air passageway 24 from syringe 12. In this combination, ball valve 44 allows air or other gases to flow from outside drip chamber 10 through air passageway 24 and into syringe 12 to replace fluid which has been dispensed from syringe 12. As previously discussed, ball valve 44 also prevents fluid in syringe 12 from flowing through air passageway 24.
[0016] Also seen in either Figure 2 or Figure 4 are ears 36 which are peripherally formed onto adapter 34 and which are suitable for engagement with a threaded luer adapter. As seen in Figures 2, 4 and 4, the ears 35 protrude peripherally and extend radially from adapter 34 and are engageable with threads 38 on connector extension 40 of syringe 12 for attachment of the syringe 12 with the adapter 34. Also, as best seen in Figure 4, the adapter 34 is provided with a slight tapered region 48 which allows for an interference connection between the adapter 34 and the nozzle-shaped extension 50 of syringe 12 when adapter 34 is urged into extension 50.
OPERATION
[0017] In its operation, the drip feed device is threadably engaged with the syringe 12 by rotating it in a manner that permits nozzle-shaped extension 50 of syringe 12 to engage with adapter 34 as shown in Figure 2. When rotated for this purpose, ears 36 on adpater 34 engage with threads 38 on connector extension 40 of syringe 12. Also, extension 50 urges into tapered region 48 of adapter 34 to provide for secure fluid tight engagement of adapter 34 with syringe 12. As best seen in Figure 2, this engagement also causes the insertion of cannula 20 into the body of fluid contained in syringe 12. Further, engagement of the drip feed device with syringe 12 in the manner above described establishes a fluid passageway 22 extending from the body of fluid contained in syringe 12 through the adapter 34 and on to the drop former 18 which is disposed in the transparent container 16 of drip chamber 10. A further appreciation of the geometry of fluid passageway 22 can be seen by reference to Figure 3 which shows a portion of fluid passageway 22 in phantom.
[0018] Figure 2 also shows that the connection of drip chamber 10 with the syringe 12 establishes an air passageway 24 from outside drip chamber 10 through air filter 28, air filter housing 26, adapter 34 and housing 32 to the body of fluid held in syringe 12. When the drip feed device is connected to syringe 12, the fluid contained in the syringe 12 will attempt to enter cannula 20. However, as fluid attempts to enter cannula 20 from syringe 12, the increase in differential air pressure within air passageway 22 urges ball valve 44 against shoulder 46 in air passageway 24 to prevent the further flow of fluid from syringe 12 through air passageway 24. On the other hand, as fluid from syringe 12 drains through fluid passageway 22, ball valve 44 moves to permit air to enter through air filter 28 and into fluid passageway 22. The air entering through filter 28 continues through air passageway 24 and forms bubbles in the fluid contained in syringe 12. In the above described manner, the body of fluid contained within air-tight syringe 12 is vented to allow an uninterrupted, regular and predictable fluid flow through fluid passageway 22. It should also be noted that the above described operation permits the withdrawal of fluid from syringe 12 without a consequent moving of the plunger assembly 42 of syringe 12.
1. A drip feed device for observing the flow of a medical fluid from a fluid source
comprising:
a drip chamber;
an adapter having a first end provided with means for engaging a fluid source and a second end having the drip chamber mounted thereon, said adapter including:
a fluid passageway extending from said first end to said second end to provide fluid communication between said fluid source and said drip chamber; and
an air passageway extending from said first end to a position outside said container to vent air to said fluid source.
2. A device according to Claim 1 in which the fluid source is a syringe.
3. A device according to Claim 1 or 2 in which the adapter is formed with means for
engaging with a threaded connecting portion of said fluid source.
4. A device according to Claim 3 in which the engaging means comprises a plurality
of protruberant ears oriented peripherally on and extending radially from said adapter
for engagement with the threaded connecting portion of said fluid source.
5. A device according to any of Claims 1 to 4 in which the adapter includes a drop
former disposed within said drip chamber.
6. A device according to any of Claims 1 to 5 in which valve means, preferably a ball
valve, is included in said air passageway to prevent fluid from flowing out via said
passageway and to permit air to enter said fluid source via said passageway.
7. A device according to any of Claims 1 to 6 in which said air passageway includes
a hollow cannula which extends into said fluid source when the adapter is engaged
therewith.
8. A device according to Claim 7 adapted for use with a syringe having a nozzle-shaped
extension for dispensing fluid contained therein, said cannula being of an external
diameter smaller than the internal diameter of the extension to permit fluid flow
therebetween and being of sufficient length to extend through said extension into
said syringe.
9. A device according to any of Claims 1 to 8 in which the drip chamber comprises
a container of a transparent plastics material, preferably a semi-rigid plastics material.
10. A device according to Claim 7, 8 or 9 in which the cannula is made from a rigid
material, preferably a metal.